Shock inducement in core barrel assembly

ABSTRACT

A core barrel assembly for a drill string comprising a core barrel, an inner tube assembly removably positionable within the core barrel, and a mechanical shock inducement mechanism for inducing at least one shock, and preferably a plurality of shocks, in the inner tube assembly. This induced shocks help reduce occurrences of blockage of core samples entering the inner tube assembly in fractured or brittle rock formations.

FIELD OF THE INVENTION

The present invention generally relates to drilling. More particularly, the present invention relates to wireline core drilling.

BACKGROUND OF THE INVENTION

Wireline core drilling is often used in minerals exploration and geotechnical drilling.

In applications where deep holes are encountered, wireline drilling systems have been developed in order to cut down on the time spent in hoisting and lowering drill strings in order to take a core sample out. In wireline drilling systems, the core sample can be removed from the bottom of the hole without removing the complete drill rod string assembly.

At the end of a core drilling operation, an overshot latching apparatus is lowered on a cable through the drill string until it reaches the core barrel. The overshot latching apparatus then latches onto a retractable inner tube assembly that is fixed in the core barrel during the core drilling operation. Upward pulling of the overshot latching apparatus triggers a release of the inner tube containing the core sample and which can then be hoisted up through the drill string.

However, when the rock being drilled is fractured or brittle, the core sample often has trouble properly entering the core barrel. If core sample blockage occurs, the inner tube assembly must be retrieved without a proper core sample and must be unblocked in order to reattempt a core drilling operation. In deep drilling operations, this retrieval of the inner tube assembly is time consuming and can cause delays in drilling operations.

Certain solutions that have attempted to address the above-mentioned problems include:

-   -   lubrification of the inner tube assembly of the core barrel;     -   the use of various drilling fluids; and     -   shaking the entire drill string from top to bottom.

However, the above solutions are not entirely satisfactory.

Hence, in light of the aforementioned, there is a need for a core barrel assembly which, by virtue of its design and components, addresses at least one of the above-mentioned needs.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a core barrel assembly which addresses at least one of the above-mentioned needs.

In accordance with an aspect of the present invention, there is provided a core barrel assembly for a drill string comprising:

-   -   a core barrel;     -   an inner tube assembly removably positionable within the core         barrel; and     -   a mechanical shock inducement mechanism for inducing at least         one shock in the inner tube assembly.

In some implementations, the mechanical shock inducement mechanism induces a plurality of shocks to the inner tube assembly.

In other implementations, the mechanical shock inducement mechanism is actuated by drilling fluid circulating under pressure within the drill string.

In some implementations, the mechanical shock inducement mechanism is actuated and coupled to a rotation of the drill string.

In other implementations, the mechanical shock inducement mechanism is actuated by an electrical power source, such as a battery system.

In other implementations, the mechanical shock inducement mechanism is actuated by a pneumatic source.

In some implementations, the mechanical shock inducement mechanism is integrated with the inner tube assembly or core barrel assembly. In other implementations, the mechanical shock inducement mechanism is not integrated with the inner tube assembly or core barrel assembly.

In some implementations, the mechanical shock inducement mechanism comprises a hammer element being actuated and impacting the inner tube assembly upon an occurrence of a blockage within the inner tube assembly. However, in other implementations the hammer element can be actuated irrespective of the state of blockage of the inner tube assembly.

In other implementations, the mechanical shock inducement mechanism includes a turbine assembly, wherein drilling fluid circulating under pressure within the drill string actuates the turbine assembly thereby causing the turbine assembly to repetitively impact the inner tube assembly, preferably because of the presence of an eccentric feature in the turbine assembly, and upon occurrence of blockage in the inner tube assembly.

This induced shock help reduce occurrences of blockage of core samples entering the inner tube assembly in fractured or brittle rock formations.

The components, advantages and other features of the invention will become more apparent upon reading of the following non-restrictive description of some optional configurations, given for the purpose of exemplification only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are side and cut views respectively of a mechanical shock inducement mechanism according to an embodiment of the present invention in an open configuration;

FIGS. 2A and 2B are side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B in a closed pre-shock configuration;

FIGS. 3A and 3B are side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B in a closed post-shock configuration;

FIGS. 4A and 4B are side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B showing internal fluid flow in an open configuration;

FIGS. 5A and 5B are side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B showing internal fluid flow in a closed pre-shock configuration;

FIGS. 6A and 6B are side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B showing internal fluid flow in a closed post-shock configuration;

FIGS. 7A and 7B are exploded side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B;

FIGS. 8A and 8B are side and cut views respectively of the mechanical shock inducement mechanism shown in FIGS. 1A and 1B in an open configuration;

FIGS. 9A, 9B and 9C are side, partially cut and detailed views respectively of a core barrel assembly and a mechanical shock inducement mechanism according to another embodiment of the present invention;

FIGS. 10A, 10B and 10C are side, partially cut and exploded views respectively of the mechanical shock inducement mechanism shown in FIGS. 9A to 9C; and

FIGS. 11A, 11B and 11C are first side, partially cut and second side views respectively of a mechanical shock inducement mechanism according to another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the following description, the same numerical references refer to similar elements. Furthermore, for the sake of simplicity and clarity, namely so as to not unduly burden the figures with several references numbers, not all figures contain references to all the components and features, and references to some components and features may be found in only one figure, and components and features of the present invention illustrated in other figures can be easily inferred therefrom. The embodiments, geometrical configurations, materials mentioned and/or dimensions shown in the figures are optional, and are given for exemplification purposes only.

Furthermore, although the present invention may be used for core barrel assemblies, for example, it is understood that it may be used for other purposes. For this reason, expressions such as “core barrel assembly””, etc. as used herein should not be taken as to limit the scope of the present invention to these applications in particular. These expressions encompass all other kinds of materials, objects and/or purposes with which the present invention could be used and may be useful, as can be easily understood.

The following reference numbers are used to designate components in the present application:

-   -   10 Mechanical shock inducement mechanism     -   11 Outer shell     -   12 Inner tube assembly     -   13 Connector     -   15 Locking element     -   17 Diffuser     -   20 Hammer element     -   21 Spring     -   31 Spindle     -   33 Inner tube cap     -   35 Thrust bearing     -   37 Shuttle valve     -   39 Spacer     -   40 Sling sawtooth clutch mechanism     -   41 Spindle bearing     -   43 Thrust bearing     -   45 Lock nut     -   47 Compression spring     -   49 Compression spring     -   51 Turbine assembly

As shown in FIGS. 1A to 8B, there is provided a mechanical shock inducement mechanism 10 for inducing at least one shock, and preferably a plurality of shocks, in an inner tube assembly according to an embodiment of the present invention. The shock inducement mechanism 10 operates within core barrel assembly for a drill string. The core barrel assembly includes a core barrel and an inner tube assembly 12 removably positionable within the core barrel 14 (note: the core barrel is only shown in FIGS. 9A to 9C).

In the embodiment shown in FIGS. 1A to 8B, the mechanical shock inducement mechanism 10 is actuated by drilling fluid circulating under pressure within the drill string. More particularly, the mechanical shock inducement mechanism 10 includes a hammer element 20 that is actuated and impacts the inner tube assembly 12 upon attainment of a built-up drilling fluid pressure within the drill string, as better shown in FIGS. 1B/4B and 2B/5B. The built-up drilling fluid pressure is attenuated and released after impact of the hammer element 20 onto the inner tube assembly 12 as better shown in FIGS. 3B/6B.

As explained above, this induced shock help reduce occurrences of blockage of core samples entering the inner tube assembly in fractured or brittle rock formations.

However, other techniques for inducing at least one or a plurality of shocks in the inner tube assembly that are known to a person of skill in the art can also be used. For example, FIGS. 9A to 10C illustrate another embodiment of the present invention. In the embodiment shown in FIGS. 9A to 10C, the mechanical shock inducement mechanism 10 is actuated and coupled to a rotation of the drill string. More particularly, the mechanical shock inducement mechanism 10 includes a sliding sawtooth clutch mechanism 40. The spring 49 is compressed by backward movement of the inner tube assembly when blockage occurs in the inner tube. This backward movement causes the sliding sawtooth clutch mechanism to engage and to repetitively impact the inner tube assembly. These impacts combined with the compression of the spring push the inner tube assembly back into position. Hence core samples that are stuck in the inner tube assembly can be dislodged.

FIGS. 11A to 11C illustrate another embodiment of the present invention. In this embodiment, the mechanical shock inducement mechanism 10 includes a turbine assembly 51, wherein drilling fluid circulating under pressure within the drill string actuates the turbine assembly 51, thereby causing the turbine assembly 51 to repetitively impact the inner tube assembly, preferably because of the presence of an eccentric feature in the turbine assembly and upon an occurrence of blockage within the inner tube assembly. In some implementations, if there is no blockage within the inner tube assembly, a spring system can prevent the turbine assembly from contacting the hammer element and therefore not unnecessarily impact the inner tube in the absence of the blockage. Once again, if there is blockage, core samples that are stuck in the inner tube assembly can be dislodged.

More generally, in other implementations, the mechanical shock inducement mechanism comprises a hammer element being actuated and impacting the inner tube assembly through a device, other than a turbine assembly, upon an occurrence of a blockage within the inner tube assembly. However, in other implementations, it can be necessary that the hammer element is actuated irrespective of the state of blockage of the inner tube assembly.

In other implementations, the mechanical shock inducement mechanism is actuated by an electrical power source, such as a battery system.

In other implementations, the mechanical shock inducement mechanism is actuated by a pneumatic source.

In some implementations, the mechanical shock inducement mechanism is integrated with the inner tube assembly or the core barrel assembly. In other implementations, the mechanical shock inducement mechanism is not integrated with the inner tube assembly or core barrel assembly.

Of course, numerous modifications could be made to the above-described embodiments without departing from the scope of the invention, as defined in the appended claims. 

1. A core barrel assembly for a drill string comprising: a core barrel; an inner tube assembly removably positionable within the core barrel; and a mechanical shock inducement mechanism for inducing at least one shock in the inner tube assembly.
 2. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism induces a plurality of shocks to the inner tube assembly.
 3. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism is actuated and coupled to a rotation of a drill string.
 4. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism is actuated by an electrical power source.
 5. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism is actuated by a pneumatic source.
 6. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism is actuated by drilling fluid circulating under pressure within the drill string.
 7. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism is integrated with the inner tube assembly.
 8. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism is integrated with the core barrel assembly.
 9. The core barrel assembly according to claim 6, wherein the mechanical shock inducement mechanism comprises a hammer element being actuated and impacting the inner tube assembly upon attainment of a built-up drilling fluid pressure within the drill string and wherein the built-up drilling fluid pressure is attenuated upon impact of the hammer element onto the inner tube assembly.
 10. The core barrel assembly according to claim 3, wherein the mechanical shock inducement mechanism comprises a sliding sawtooth clutch mechanism, and further comprises a spring that is compressible by backward movement of the inner tube assembly upon an occurrence of blockage in the inner tube, the backward movement of the inner tube assembly causing the sliding sawtooth clutch mechanism to engage and to repetitively impact the inner tube assembly, the impacts combined with the compression of the spring pushing the inner tube assembly back into an original position.
 11. The core barrel assembly according to claim 6, wherein the mechanical shock inducement mechanism comprises a turbine assembly, wherein drilling fluid circulating under pressure within the drill string actuates the turbine assembly thereby causing the turbine assembly to repetitively impact the inner tube assembly.
 12. The core barrel assembly according to claim 11, wherein the turbine assembly comprises an eccentric feature.
 13. The core barrel assembly according to claim 11, the turbine assembly repetitively impacts the inner tube assembly upon an occurrence of a blockage within the inner tube assembly.
 14. The core barrel assembly according to claim 1, wherein the mechanical shock inducement mechanism comprises a hammer element being actuated and impacting the inner tube assembly upon an occurrence of a blockage within the inner tube assembly. 